Pneumatic impact-tool



W. BURLINGHAM.

PNEUMATIC IMPACT TOOL.

APPLICATION FILED FEB-16,1915.

1 ,357,31 2, Patented Nov. 2, 1920.

, 4 SHEETS-SHEET I.

z- 0 INVENTOR By? a I ATTURNt (T w. BURLINGHAM.

PNEUMATLC IMPACT TOOL.

APPLICATION FILED FEB. l6| I915.

w. BURLINGHAM. PNEUMATIC IMPACT TOOL. APPLICATION FILED FEB-16,1915.

Patented Nov. 2, 1920.

4 SHEETS-SHEET a. I

INVENTOR WITNESSES ATTORNEYS tion with which I employ a novel construction of single valve which'serves not only as a high pressure inlet controlling valve, but also as a low pressure exhaust controlling valve, all in conjunction with a receiver common to said valve and its adjuncts and to said high pressure and low pressure cylinders, the foregoing elementsbeing eolhr cated with my novel construction of tool cylinder, which .is preferably provided with a grasping handle and a throttling valve mechanism of suitable construction at its rear end, the forward end of said tool cylinder being preferably open for the insertion of the shank of the chisel. button set or other working tool.

As a result of this collocation of my novel construction of high pressure inlet controlling and low pressure exhaust controlling single valve, in combination with a receiver and my novel construction of high pressure and low pressure cylinders and hammering piston, provided with a small diameter and a large diameter portion which at its forward stroke has the function of a tandem piston and in its return stroke has the function of a differential piston, I am enabled to effect a very large saving over the expense in operation of pneumatic tools now in use, and to utilize to a great extent the expansive effect of the compressed air or other motive,

fluid which is initially used at high pressure, and, as stated, I further simultaneously employ high pressure live air and low pressure air to augment the velocity or momentum of the hammering plunger prior to or during the act of striking its blow upon the shank of the working tool, my novel piston or plunger in its outward stroke having the function of a tandem piston, the piston being so designed that on its return stroke it has the function of a differential piston and is returned toward the tool handle by the preponderance of pressure upon the greater area.

To the above ends, my invention therefore consists in its broad aspects of a novel fluid distribution system for pneumatic hammers, controlled by a single valve, wherein I utilize to a greater extent than heretofore, the expansive properties of the compressed air employed to effect the reciprocations of the hammering piston.

My invention further consists of a novel percussion or impact tool wherein the compressed air is controlled by: a single valve and is used expa'nsively in a novel manner in conjunction with my novel valve, so that my novel construction of hammering piston acting as a tandem piston on its forward stroke, is impelled directly on the shank of the working tool during its striking blow by the high pressure live air and by low pressure air simultaneously applied thereto.

It further consists of a pneumatic hammer comprising my novel construction of single distributing valve in conjunction with a hammering piston having differential piston areas, whereby said piston is returned from the shank of the working tool toward the handle by reason of the preponderance of low pressure motive fluid upon the large differential area of the piston.

It further consists of such a tool having the characteristics above referred to, wherein a single valve is employed, whereby the high pressure live air is substantially only used for initially impelling the tandem or differential hammering piston toward the working tool.

It further consists of an improved arrangement of the operative parts of a pneumatic impact tool whereby the employment of a single valve controlling my novel fluid distribution system enables me to reduce the length of the tool as compared with other tools of similar power, the weight of the tool proportionate to its power being also greatly reduced, which is a very desirable feature in mechanisms of this general character.

It further consists of a novel construction of grasping handle having a chamber formeo therein for the reception of a single valve controlling my novel fluid distribution system common to said valve and the coacting ports and passages in the barrel of the tool.

It further consists in the novel combination of a grasping handle comprising a throttle valve for controlling the initial admission of motive fluid to the tool, said handle also containing a novel construction of valve chamber and single valve for controlling my novel fluid distribution system.

It further consists of a novel construction of a barrel having passages therein serving as a receiver in conjunction with a novel construction of grasping handle having a single valve therein controlling the fluid distribution system, whereby the reciprocations of the hammering piston are effected.

It further consists of a novel construction of valve and its adjuncts.

It further consists of other novel features of construction, as will be hereinafter pointed out in the claims.

For the purpose of illustrating my inven tion, I have shown in the accompanying drawings, certain forms thereof which are at present prefea'ed by me, since the same will give in practice satisfactory and reliable results, although it is to be understood that the various instrumentalities of which my invention consists can be variously arranged and organized and that my invention is not limited to the precise arrangement and organization of these instrumentalities as herein shown and described.

Figure 1 represents a longitudinal seetionalv view of a compound single valve pneumatic hammer, embodying my inven tion.

Fig. 2 represents a plan view of Fig. 1.

Fig. 3 represents a longitudinal sectional view ol the barrel or cylinder showing the exhaust port from the forward end of the cylinder in advance of the piston together with the ports for operating the valve.

lflig. 4 represents a longitudinal section of the cylinder showing the port connecting the high pressure cylinder through the valve to the forward cylinder in advance of the piston.

Fig. 5 represents an end view'o'l. the cylinder or barrel, which abuts against the handle.

Fig. (5 represents a transverse section on line iii-m l, with valve removed.

Fig. 7 represents a longitudinal sectional view of the single valve employed.

Fig. 8 represents an inverted plan view of the closure for the valve chamber, showing the exhaust ports therein.

Fig. 9 represents a-section on line 3 -y l ig. 8, showing the cylinder for the valve actuating plunger.

ll) represents a perspective view of the valve actuating plunger employed in conjunction with the valve seen in Fig. 7.

Fig. ll. represents a diagrammatic view showing the cycle of operation and relative arrangement of ports and passages employed in conjunction with my novel single valve, showing the piston at the beginning of its downward stroke and the valve positioned to admit air to both cylinders.

Fig. 12 represents a diagrammatic view similar to Fig. 11 but showing the piston in the act of striking a blow and the valve positioned. to permitexhaust from the low pressure cylinder to the atmosphere and ad Knitting air from the high pressure cylinder to the cylinder in advance of the low pressure piston for returning the piston to the position seen in, Fig. 11.

Fig. 13 represents a side elevation partly in section showing my novel single valve and compound. cylinders as adapted to an open handled tool.

Similar numerals of reference indicate corresponding parts in the figures. 1

Referring to the drawings, i

l designates my novel construction of compound single valve pneumatic tool, the same comprising a barrel 2 and handle member 3. which may be of the ole ed type as shown in Fig. l, or of the open type, as shown in Fig. The barrel 2 is provided with cylinders of different bores 4; and 5 whereby a high pressure cylinder a and a low pressure cylinder 5 are formed. In the forward end of the barrel I locate the tool shank bush 6 having the flanged nut 7, whereby said bush can be screwed into said .the motive fluid in the compound cylinders l and the same comprising a body portion preferably made hollow and. having the closed end 18, and the open end 19, and provided with the annular grooves 20 and 21., whereby the distribution of the motive iiuid for the op ration of the hammer is ctl'ected.

253 and Ql designate valve rings, the

circuni'lerential ed es of which control the admission and exhaust of the motive fluid for the operation of the hammer. In the open end of the valve, 1 provide a chamber 2:? having a seat or shoulder 26 for the reception of the flange 27 of the plunger 28, which is guided in the chamber29 of the extension 30 of the closure 81, whose construction will be understood from Figs. 1, 8 and 9. said closure having the threaded head 32, through which extend the exhaust ports 33, which in the present instance are four in number, said head being also provided with the annular groove 3% therein, ich has the ports 35 communicating thereh, which supply a constant fluid pressure u i u it from the main supply 36 to the chamber 29 above the valve actuating plunger 28 by means of the port 87 and passages 38 and l0 designates a valve lining which l. preferably employ and which is provided with ports coacting with the valve, as will be explained, said valve and. lining being in the present instance located in that portion of the hanrlle nearest the barrel, although it will be evident that the valve and its adjuncts might be located in any other desirable position or portion of the tool. It will also be evident that my novel valve mechanism may be employed in conjunction witl a handle 3 of the closed type, as seen in Fig. l, or it may be employed with an open handle ll oi? the type seen in 13. In both types oi? said handles the pressure supply duct is indicated at and the flow of the motive fluid is controlled by the manually operated. or controlled throttle valve 42, commonly employed in handles oi: this gcne'al character.

the barrel 2 by any desired means but I preit'erably employ the construction seen in F 1g.- 1, wherein I have shown said socket in The handle socket may be secured to threaded engagement with said barrel, the parts being locked in assembled position by the engagement of the pin 4. 1 with the hole 72, said pin being held in the desired posi tion the tension of the spring 45 'on' the pin plunger 16. In the rear end of the barrel 2, T locate the receiver -17, which consists of a plurality of longitudinally extending chambers, in the present instance five in number, as seen in Fig. 5, connected together, in the present instance, by slots 18, as seen in Figs. 1 and 5, thus forming one common receiver chamber.

The cycle of my novel motive fluid dis tribution system which occurs during the reciprocal movements of my coacting motive fluid distributing valve and hammering piston will now be explained and will be clearly understood from the foregoing description and the following reference to the diagrammatic views seen in Figs. 11 and 12.

Referring first to Fig. 11, the hammering piston 13 is shown in position to begin its outward stroke toward the shank of the working tool, and the valve 17 is shown in such extreme position as to admit air to both cylinders and to permit exhaust to the atmosphere through the ports 38 from the cylinder in advance of the low pressure piston. Upon opening the throttle 4-2, the motive fluid enters the main-supply duct 36, and passes thence through passages 37, 38, 39, groove 841, and passages 35 to the top of the chamber 29, back of the end of the plunger 28, which moves the valve 17 into the position seen in Figs. 1 and 11. The live air now passes through the passage 49, and the port 50 into the annular groove 20 of the valve 17, and flows through the port 51, the passage 52 and port to the end of I the high pressure cylinder 1 and forces the piston toward the shank of the working tool. The exhaust from the cylinder in advance of the low pressure piston passes through port 5 1, passage 55 and port 56 into the chamber 57 at the end of the valve and thence to the atmosphere through the pasages 83. During this first stroke of the piston the receiver 17 has no pressure therein and therefore the low pressure cylinder 5 has no pressure therein.

When the piston has reached the end of its outward stroke, live air in the high pressure cylinder flows through passage 58 to the receiver 17, thus equalizing the pressure in said receiver and high pressure cylinder. Atthe same time the live air passes from the high pressure cylinder 41 through the passages 59 and 60 to the closed end 18-of the valve 17, forcing the latter from the position seen in Fig. 11 to the position seen in Fig. 12, the piston 13 being also now in the position seen in Fig. 12.

Referring to- Fig. 12, the hammering piston 13 is shown in position to begin its inward stroke away from the shank of the working tool and valve 17 is shown in such other extreme position as to exhaust the air from the low pressure cylinder 5 through the passage 70, port 69, annular groove 21 and port 71 to, the atmosphere. At the same time, the air from. the high pressure cylinder e exhausts through passages 58, 52, port 51,, annular groove 20 of the valve 17, port 61, passage 62 and port 63 to the cylinder in advance of the low pressure piston, thereby equalizing the pressure in the high pressure cylinder and the cylinder forward of the low pressure piston 15.

By reason of the differential areas of the pistons 1 1 and 15, the preponderance of pressure upon the larger forward area causes the piston to move inwardly or away from the shank of the working tool, said piston now being in the position seen in Fig. 11. lVhen the, piston has returned to the position seen in Fig. 1, the annular groove 61 therein registers with passages 65 and 66, thus allowing the air pocketed back of the closed end 18 of the valve 17 to exhaust through passages 60 and 65, annular groove 64 and passage 66 to the atmosphere. The opening of the exhaust passages last described, causes a reduction of the pressure on the closed end 18 of the valve 17 whereupon the preponderance of the pressure upon the opposite end of the valve due to the pressure upon the plunger 28 through the medium of the ports and passages communicating with the chamber 29, causes said valve to assume the position seen in Fig. 11. The foregoing description is definitive of the first outward and inward stroke of the hammering piston and the first complete travel of the valve to and fro, these movements coacting in such a manner as to permit the correct distribution of the motive fluid. The receiver .47 was filled with air, at the end of the first outward stroke of the piston 13, through the passage 58. On the second outward stroke and all succeeding strokes, the air from the receiver 17 flows through passage 67 and port 68, annular groove 21, port 69 and passage 70 to the low pressure cylinder. It will thus be seen that whilethe energy of the first outward stroke of the hammering piston is due solely to live air pressure on the high pressure piston, this energy on the second and all we ceeding outward strokes of said piston is augmented by the energy due to the air from the receiver acting on the low pres sure piston. The cycle of the air distribution in the second and succeeding outward strokes of the piston is the same as that of the first outward stroke with the exception that the air from the receiver is admitted through the passages heretoiore described to the low pressure piston.

it will be apparent from the foregoing that high pressiu'e air and low pressureair simultaneously cooperate to augment the operative outward stroke of the hammering piston the latter in its outward movement toward the shank of the working tool having the function of a taiiidem piston. Low PtGf-SUK'G air only is employed to return the piston from the shank oi the hammering tool, said return being; effected by the preponderance of pressure upon the large or for ard area of the hammering piston. The only (.XllilllSt is of low pressure air, which has performed its functions directly and expansively. After the high pressure air has "tori-ed the piston down or outwardly to deliver the blow upon the shank of the l tool. a part of the expanding air is die employed to return the piston, the piston on its return movement having the "function ot a differential. piston while a 1:- et said expanding air is stored away in toe receiver 47 to be employed to act against the low pressure piston oi the plunger in the driving stroke of the latter. As stated, no air being exhausted excepting low pressure air which has been used in a low pressure cylinder and in the valve mher, very high eliiciency is obtained 1 using the air at its original pressure and thereupon again by compound use of the expanded air exhausted from the high pressure cylinder.

By forming the receiver member -47 from. longitudinal bores in the barrel. 2 of the tool and connecting them by the ports or passages such receiver does not add to the length or "Weight of the tool, and the existence oi? the bores or passages forming the receiver .17 will materially reduce the weight of the tool by cutting away otherwise useless material.

Ry the employment of the single valve in the body portion of the grasping handle and making such valve hollow and arranging the valve preterably transversely to the barrel, the over-all length of the tool is also reduced. and the weight of the handle is considerably diminished. is the hammering piston is eturned by the expanded liv air acting against diiterential. piston areas, the return or upstroke of the hammering piston is cushioned and the shock and vibration oi. the tool are considerably reduced, thereby easing the hold of the tool to the work.

l have found y caretul experiments and calculation. that my novel construction of hammer will, in addition to striking a harder blow, reduce the consumption very greatly below the consumption of similar tools. While the outward stroke of the hammering piston is performed on the compound principle, employing live air and partly expanded air, or, in other words, is effected by the action oi high pressure and low pressure motive fluid combined, the compound principle is not employed for the return stroke, which is performed by the diiierential action of the expanded or low pressure fluid.

it will further be seen that by making my novel construction of single valve hollow and providing the same with the heads or pistons 2:2, 23 and. 25!: of the same diameter, the same can be readily manufactured and ground, and the valve lining or casing can he also readily and cheaply manufactured.

By the employment of my hammering piston in conjunction with the high and low pressure cylinders having my novel fluid distribution system controlled by a single valve, it will be seen that I provide an ethcient means for equalizing the air pressure in the high pressure cylinder and the low pressure cylinder between the striking end of the differential piston and theshank of the working tool, thereby utilizing the air in the high pressure cylinder after the re ceiver has been filled to return the hammer ing piston.

I desire to call special attention to the fact that my invention in its broad aspects is especially applicable to that type of light or portable, manually held impact tools especially adapted for riveting, chipping, call;- i g', hammering or analogous uses, wherein the forward end of the barrel is open for the insertion of the shank of the working tool, and wherein the hammering piston impacts preteralny directly upon said shank of the rivet set, chisel or other working tool.

My present invention. is diilerentiated from my Patent No. 1,123,678, granted January 1915, wherein I have shown two distribution valves employed and have shown the receiver as located in an extens'ion of: the grasping handle and while tools embodying the subjectmatter of my prior patent aforesaid have been "found to be practicable and therefore commer ally successful and to effect a saving oi a very large per cent. in the air consumption over simitools in use, l p efer for some reasons to employ my present construction of pneumatic tool, since by the employment of :1 single valve, I am. enabled to reduce the number oi? mcvin parts and to also simplify and lighten tool structure 7 My present tool, in addition to possessing all. the advantages of my prior patent hereinabove referred to, possesses the additional advantages othaving fewer moving parts, and has been found by calculation to be somewhat lighter and even more efiicient than the tools constructed under my prior patent aforesaid;

Generally speaking, among the advantages of my present invention over my prior patent aforesaid, as well as other prior devlces, are 7 1st. Decrease in weight;

2nd. Decrease in cost of manufacture;

3rd. Decrease in the number of moving parts;

4th. Decrease in the friction of the air by reason of shorter passages;

5th. Decrease in liability of getting out of order by reason ofthe small number of parts;

6th. It can be assembled and disassembled quicker; and

7th. Decrease in diameter of the high pressure cylinder, thus making it possible to use a lighter piston, with consequent advantages in effectiveness.

In the hammer of my prior patent aforesaid, I designed the same so as to out off the air supply at about the middle of the stroke in the high pressure and low pressure cylinders which necessitated the preferable em ployment of two valves, one to operate to cut olf the air. supply to the high pressure and low pressure cylinders, and the other to'open these cylinders to exhaust at the end of the stroke.

In order to employ the broad principle of my invention aforesaid in a tool having a single valve, I therefore reduce the diameter of the high pressure cylinder in such proportion as to supply the same work in the high pressure cylinder taking air the full stroke as was formerly taken in the high. pressure cylinder of my prior tool to the point of cut off. 'l he pressure in the high pressure cylinder of my present invention employing a single valve at the end of the stroke is equal to th initial pressure, and the airin the receiver expands only in both the receiver and low pressure cylinders during the entire stroke. Dy this arrangement, the times of cut off and exhaust are made substantially simultaneous and the use of a single valve is made possible and practical and commercially successful.

I am aware that it has heretofore been proposed to use compressed air somewhat as in a compound engine in rock drills or similar structures, which employ massive and heavy reciprocating-engines frequently weighing several hundred pounds, and which are required to be supported upon a suitable-tripod, and wherein the drill or otherworklng tool is connected to or reciprocates directly in unison with the reciprocating piston. My present invention is,

however, clearly differentiated froinmassive tools of this character having a comparatively slow moving PlSlJOl'l, for the reason that my present device is particularly applicab e to the small, manually held and manually controlled riveters or chipping tools,

wherein the tool is usually supported in the hands of the operator only, and wherein the hammering piston reciprocates with great rapidity and impacts directly upon the shank of the chisel, rivet set or other working tool.

My present invention is further differentiated from the compound rock drills having the comparatively slow moving piston aforesaid or the ordinary compound engine in the matter of the motor fluid distribution, for the following reasons In a compound engine, the expanded fluid of the high pressure cylinders after the stroke has been completed exhausts in its entirety into the receiver during practically all of the return stroke, while in'my present invention, the cycle of the motor fluid distribution is quite different, since I employ but a single valve, and I take a part of the expanded air of the high pressure cylinder to the receiver, and from this receiver the air istaken for the upper end of the low pressure cylinder to drive the piston against theshank of the working tool on its working stroke. The remainder of the expanded air left in the high pressurecylinder after the receiver is filled is'used to return the differential plunger by a differential or prethe pressure in the chamber in advance of the low pressure cylinder on the forward end of the piston being equalized through a con necting passage.

By the employment of partly expanded air upon the hammering piston during the period ,it is striking the blow, wherein it is having the functionof a tandem piston, the velocity and momentum of the recipr'cating plunger are greatly augmented during the period when such increase of power is-desirable'aiul by thecmployment of the di'derential action of the expanded and low pressure fluid to return the hammering piston after its impact against the shank of the w ring tool, the expansive action of the motive iiuid is utilized tothe retest possible ezuyent as will be apparent to those skilled in the 1,

It will further be apparent in my invention, that by the employment the receiver and its adjuncts, the extensive vibration heretofore incident to theoperation of tools of this character, particularly during riveting and chipping, is eliminated to a great extent. 7 v

So far as 1 am aware, 1 am thelirst in the art to employ in a pneumatic tool. of the distribution.

handle member having therein a single thelive air and' character heretofore described, a single 1 '11 1 valve controlling the cycleor motor time valve controlling the distribution of the motor fluid in the manner heretofore described.

I am also the first in the art to employ a handle member having a single valve therein in conjunction with a barrel having a re ceiver and. the hereinbefore described collocation of ports and passages.

I am also the first in the art to employ a handle member having therein a single valve controlling the motor fluid distribution system hereinbefore described when combined with a barrel having a high pressure cylinder, a low pressure cylinder, and a receiver therein, said cylinders being provided with a plunger of the character described.

I am also the first in the art to employ in a portable, manually held pneumatic hammer having a barrel provided with its front end open to receive the shank of the working tool, the features of a hammering piston acting as a tandem piston in its forward stroke, and a differential piston in its rearward stroke, combined with a single controlling valve and a receiver, whereby motive fluid may be used expansively as described, and my claims to these features are therefore to be interpreted. with the corresponding scope awarded to a pioneer invention.

' I am also the first in the art to employ a tandem hammering piston having two varying areas in line with each other, the worl ing'pressure to drive the piston forward and strike its blow upon the working tool acting on the same side of each piston simultaneously, said piston being returned by the preponderance of pressure upon its larger area, in conjunction with a single valve of any character whatsoever.

I am also the first to employ a single valve in compounding the air into two or more cylinders.

It will now be apparent that I have devised a new and useful pneumatic impact tool embodying the features of advantage enumerated as desirable in the statement of the invention and the above description, and while I have shown and described certain forms thereof which will give in practi 2, satisfactory and reliable results. it is to be understood that the same is susceptible of modification in various particulars without departing from the spirit or scope of the invention or sacrificing any of its advantages.

rotate in said cylinder, a single valve for in the opposite air pressure.

controlling the distribution of motive fluid, and means coacting with said single valve to utilize the energy left in the air after it has been initially used in one cylinder, for the purpose of augmenting the energy of said piston.

2. In a compound pneumatic impact tool, a barrel, a large diameter cylinder therein, a small diameter cylinder, a large diameter piston and a small diameter piston fitting said cylinders, the sum of the pressure on the rear working faces of the piston causing the striking blow, and the difference of pressure on the opposite extremities of said piston effecting the return of said piston, and a single valve controlling the air distribution to and from said cylinders, in combination with means coacting with said single valve to utilize the energy left in the air after it has been initially used in one cylinder for augmenting the energy of said piston.

3. In a compound pneumatic impact tool, a barrel having its forward end open to receive the shank of the working tool,"and provided with cylinders of dilferent diameters, a piston of varying diameter conforming to said cylinders, a receiver, and a single valve effecting the entire distribution of motive fluid to and from said cylinders, in com-- bination with means coacting with said single valve to utilize the energy left in the air after it has been initially used in one cylinder for augmenting the energy of said piston.

l. In a pneumatic impact tool, a barrel. cylinders therein, a piston in said cylinders, a receiver formed in said barrel enteriorly to said cylinders, and a single valve for controlling the flow of the motive fluid to and from said cylinders and into and from said receiver.

5. In a pneumatic impacttool, a barrel, cylinders therein, a piston in said cylinders, a receiver formed in said barrel, and a single valve for controlling the flow of the mo tive fluid to and from said cylinders and into and from said receiver, said single valve being operated in one direction by the motive fluid. at substantially the receiver pressure, in combination with means coach ing with said single valve to utilize theen ergy left in the air after it has been initially used in one cylinder for augmenting theenergy of said piston.

6. In a pneumatic impact tool, a barrel, cylinders therein, a piston in said cylindeis, a receiver formed in said barre], and-a single valve for controlling the flowof the m0 tive fluid to and from said cylinders and into T and from said receiver, said val-febeing operated in one direction by the motive'fluid at substantially the receiver pressure, and direction by constant live 7. In a pneumatic impact tool, a small diameter cylinder, a large dlameter cylinder, a small diameter and large diameter piston adapted'to reciprocate in said cylinders, areceiver connected to receive expanded motive fluid from the small diameter cylinder, and a single valve adapted to control the flow'of live motive fluid to said small diameter cylinder and expanded motive fluid from said large diameter cylinder.

8. In a pneumatic impact tool, a plurality of cylinders of different diameters, pistons of different diameters fitted to reciprocate in said cylinders, a receiver connected to receive expanded motive fluid from a small diameter cylinder, passages adapted to connect said receiver with an end of said large diameter cylinder, and a single'valve adapted to control the flow of live motive fluid to said small diameter cylinder.

9. In-a pneumatic impact tool, a small diameter cylinder and a large diameter cylinder, a plunger having a small diameter and a large diameter piston reciprocable in said cylinders, a receiver connected to receive expanded motive fluid from the small diameter cylinder, a single valve,;a passage controlled by said valve te admit expanded motive fluid from the receiver to the upper or inner face of the large diameter piston,

1 and a passage to simultaneously admit live motive fluid to the upper or inner face of the small diameter piston, in combination with means coacting with said single valve to utilize the energy left in the air after it has been initially used in onecylinder for augmenting the energy oisaid piston.

10. In a pneumatic impact tool, a small diameter and a large diameter cylinder portion, a plunger havinga small diameter and a large diameter piston respectively reciproeable in said cylinder portions, a receiver having a passage leading to it from the forward portion of the small diameter cylin der, and a single valve controlling the flow of live motive fluid to the inner end of the small diameter cylinder, and expanded motive fluid from the receiver to the inner face of the large diameter piston.

11. In a pneumatic impact tool, a barrel,

a small diameter high-prcssure cylinder, a.

large diameter low-pressure cylinder, a piston having small diameterand large diameter portions respectively reciprocable'in said cylinders, a receiver, and a single valve .connected to intermittently admit live motive fluid at the inner end of the high-pressure cylinder and to intermittently admit expanded motive fluid from said receiver to an end of said low-pressurecylinder to drive said piston outwardly, said valve having 7 constant fluid pressure on an end thereof.

12. In a pneumatic impact tool, a barrel, small diameter. and large diameterccylinders therein, a piston having small and large diameter portions respectively reciprocable. in said cylinders, a receiver in said barrel connected to the outer portion of the small diameter cylinder to receive expanded m0- tive fluid from the latter, a valve chamber connected to the forward ends of the large diameter cylinder and to the inner end of the small diameter cylinder, and a single valve in said valve chamber adapted to con-j diameter cylinder to receive expanded motive fluid from the same, a single valve chamber connected .to the mner and outer ends of said large cylmder, and a single valve reciprocable in said chamber to intermittently admit motive fluid at the inner end of said small diameter cylinder and to intermittently connect the inner end of said large diameter cylinder to exhaust.

14. In a pneumatic impact tool, a barrel, small diameter and large diameter cylinders therein, a piston having small and large diameter portions respectively reciprocable in said cylinders, a receiver in said barrel having a passage to it from the outer por tion of said small diameter cylinder, a single valve chamber having an inlet for the motive fluid and ports connected to the inner ends of said cylinders and an exhaust,and a single valve in said valve chamber-adapted to admit motive fluid to the small diameter piston and expanded motive fluid from the receiver to the inner portion of the large to an exhaust, said valve being actuated in one direction by constant pressure, and in the opposite direction by motive fluid which has driven said piston outwardly.

15. In a pneumatic impact tool, a barrel having its forwardend open to receive the shank of the working tool, and having cylinders of different diameters, a piston having portions of different diameters to reciprocate in said cylinders, a receiver, and a single valve by which the live motive fluid can be admitted simultaneously to each cylinder, and also exhausted simultaneously "from each cylinder.

16. In a pneumatic impact tool, a barrel,

high pressure and low pressure cylinders therein, a grooved piston located in said cylinders, a valve chamber, a receiver in said barrel, and a single valve in said chamber controlling .ports common to: said 2 cylinders,

valve chamber and receiver, said valve being actuated in one direction by constant live air pressure upon one end thereof, and intermittent live air pressure upon the other end thereof, the groove in said piston permitting exhaust from one end oi said valve.

17. in a pneumatic impact tool, a barrel, high pressure and low pressure cylinders therein, a grooved pistra in said cylinder having a small diameter portionand a large diameter portion, a receiver, a valve chamber and a single distribution differential valve therein controlling ports common to said cylinders, valve chamber and receiver, said piston acting on its outward stroke as a tandem piston and on its inward stroke as a differential piston, said latter movement being effected by a preponderance of pressure on the large area of said piston, and the groove in said piston permitting exhaust from the larger end of said valve.

18. In a pneumatic impact tool, a valve chamber, a single differential valve therein, a plunger coacting with said valve, a hammering piston having a groove therein coacting with the larger end of said valve, means for constantly introducing live air aressure upon an end of said plunger, thereby actuating said valve, means for intermittently introducing pressure on the opposite end of said valve, a barrel for the reception of said hammering piston therein, and a receiver, said barrel, valve chamber and receiver hav ing ports and passages common to each other, and the groove in said piston. permitting exhaust from the larger end of said valve when said piston is in its rearmost position.

19. In a compound pneumatic impact tool, a barrel having a high pressure cylinder and a low pressure cylinder therein, a piston therein provided with a groove and having a small diameter portion and a large diameter portion, a receiver, a valve chamber, a single differential valve there's, controlling ports common to said cylinders, valve chain ber and receiver, the groove in said plunger permitting exhaust from the larger area of said valve, a plunger cooperating with said valve, a plunger chamber, having live air constantly admit ed thereto, and a closure for said plunger chamber, said closure naving constantly open exhaust ports therein.

2 in a pneumatic impact tool, a barrel having a high pressure cylinder and a low pressure cylinder therein, a grooved hammering piston therein having a small and large diameter portion, a receiver also located in said barrel, a valve chamber, single differential valve in said valve chamber, controlling ports common to said cylinders, valve chamber and receiver, a plunger cooperating with said valve, means for exerting constant live air pressure on said plunger and valve in one direction, and

means for exerting an intermittent pressure on the larger area of said valve in the opposite direction, the exhaust from the larger area of said valve being permitted by the groove in said piston, when the latter reaches one oi its extreme positions.

21. In a pneumatic impact tool, a barrel having a high pressure cylinder and a low pressure cylinder therein, a piston therein having a small diameter portion and a large diameter portion, a receiver, a valve chamher, a single hollow dillerential valve therein, controlling ports common to said cylinders, valve chamber and receiver, a plunger having a flange thereon coacting with said valve, means for exerting constant pressure on said valve and plunger in one direction, means for efi'ecting the actuation of said valve in the opposite direction, and means controlled by said piston for permitting exhaust from the larger area oi said valve when said piston reaches the extreme of its inner stroke, said piston acting as a tandem piston on its forward stroke, and as a differential piston on its inner or return stroke.

22. In a pneumatic impact tool, a barrel, small diameter and large diameter cylinders therein, a piston having small diameter and large diameter portions respectively reciprocable in said cylinders, a receiver connected to receive expanded motive fluid from the small diameter cylinder, a single, hollow, differential valve, and passages controlled by said valve and connected to admit live motive fluid to the inner end of the small diameter cylinder and expanded motive fluid from the receiver alternately to the inher end of said large diameter cylinder, a closure for said valve chamber, having constantly open ports therein and a plunger chamber, a plunger in said plunger chamber coacting with said valve, means for introducing constant live air pressure on said plunger and valve to move them in one direction, and means for permitting the exhaust from the larger end of said differential valve, when said piston reaches one extreme of its stroke.

28. In a pneumatic impact tool, a barrel having high and low pressure cylinders therein, a grooved hammering piston in said cylinders having small and large diameter portions, a receiver also located in said barrel, a valve chamber, a single differential valve therein, controlling ports common to said cylinders, valve chamber and receiver, a closure for said valve chamber having constantly open exhaust ports therein, a plunger cooperating with said valve and contained in a plunger chamber formed in said closure, means for constantly introducing live air pressure into said plunger chamber to actuate said plunger and valve in one direction, and means for intermittently introducing pressure upon the larger area of said valve to actuate the latter in the opposite direction, the exhaust from said larger area being controlled by the groove 5 in said piston when the latter reaches the end and open at the other, said open end havinga shoulder therein adapted toreceivc the flange of a coacting plunger.

26. The combination of a valve chamber,

7 a closure therefor, a plunger chamber in said closure, the latter having constantly open exhaust ports therein, a plunger in said chamber, means for admitting constant pressure into said plunger chamber, a valve having one end closed in said valve chamber and coacting with said plunger, means for intermittently admitting and exhausting air to and from said closed end of said valve, a barrel having high and low pressure cylinders therein, and a piston in said cylinders controlled by said valve. 1

27. The combination of a valve chamber, a closure therefor, a plunger chamber in said closure, the latter having constantly open exhaust ports therein, a plunger in said chamber, means for admitting constant pressure into said plunger chamber, a differential valve in said valve chamber and coacting with said plunger, said valve having one end closed, means for intermittently admitting and exhausting air to and from said closed end of said valve, a barrel having high and low pressure cylinders therein, a receiver, and a piston in said cylinders controlled by said valve.

28. In a compound pneumatic impact tool, a valve chamber, a closure therefor, a plunger chamber in said closure, said closure having constantly open exhaust ports therein, a plunger in said chamber, means for admitting constant pressure into an end of said plunger chamber, a hollow, difiierential valve in said valve chamber coacting with said plunger and having its end opposite to said plunger closed,,means for directing constant pressure on said plunger and one end of said valve, a barrel, a hammering ger chamber in said closure, said closure having constantly open exhaust ports therein, a plunger 1n said chamber, means for admitting constant pressure into' an end ofsaid chamber, a hollow differential valve valve chamber, coacting with said plunger and having its end opposite to said plunger closed, means for directing constant pressure on said plunger and one end of said valve, a barrel, a hammering piston therein, and means for intermittently admitting and exhausting air from the closed end of said valve, in combination with a receiver, and passages common to said receiver, barrel and valve chamber.

30. In a compound pneumatic impact tool, barrel,a hammering piston therein, receiver in said barrel, a valve chamber, a single valve in said valve chamber, provided with a plurality of grooves and rings, means for introducing constant pressure on one end of said valve, and means controlled by said piston for permitting intermittent pressure and exhaust upon'the opposite end of said valve. 7

31. In a compound pneumatic impact tool, a barrel, a grooved hammering piston there in, a receiver in said barrel, a' valve chamber, a single valve in said valve chamber, provided with a plurality of grooves and rings, means tor introducing constant pressure on one end of said valve, and means controlled by said piston for permitting intermittent pressure and exhaust upon the opposite end 01 said valve.

32. In a compound pneumatic impact tool, a barrel, high and low pressure cylinders therein, a hammering piston having high and low pressure areas thereon, a receiver carried by said barrel, a valve chamber, a single valve therein, )I'OVldGCl with a plurality of grooves and rings, means for. introducing constant pressure upon one end 01 said valve, and means forpermitting intermittent pressure and exhaust upon the opposite end of said valve.

In a compound pneumatic impact tool, high and low pressure cylinders therein, a hammering piston having high and low pressure areas thereon, a receiver carried by said barrel, a valve chamber, a single valve therein provided with a plurality of grooves and rings, a plunger coacting with said valve, means for introducing constant pressure upon one end of said plunger and valve, and means controlled by said piston for permitting intermittent pressure and exhaust upon the opposite end of said valve.

3%. In a compound pneumatic impact tool, the combination of a cylinder, a piston thereplunger in said in, a single valve, a receiver, and means for operating said piston by means of the pressure of the expanded air in the receiver.

35. In a compound pneumatic impact tool, a cylinder, a piston therein, a single valve, a

receiver, and means for operating said pis ton by the pressure of the expanded air in said receiver, said valve being actuated in one direction by constant pressure and in the opposite direction by pressure and exhaust passages controlled by said piston.

36. In a compound pneumatic impact tool, a small diameter cylinder, a large diameter cylinder, a small diameter and large diameter piston adapted to reciprocate in said cylinder, a single valve, and means controlled by said single valve for using energy left in the air after it has been used in one cylinder, for augmenting the energy of said piston.

37. In a compound pneumatic impact tool, a small diameter cylinder, a larger diameter cylinder, small diameter and larger diameter pistons adapted to reciprocate in said cylinders, a single valve, and means controlled by said single valve for using the energy left in the motive fluid after it has been used in any of the cylinders for augmenting the blow of said plungers. 1

558.v In a compound pneumatic impact tool having open ends, a plurality of cylinders of varying diameter, pistons of varying diame ter adapted to fit said cylinders, a single valve, and means controlled by said single valve for utilizing the remainder of the energy left in the expanded air after it has been exhausted from the initial pressure cylinder to increase the energy of the stroke of the piston without increase of consumption of the free air.

39. In a compound pneumatic impact tool, a small diameter and a large diameter cylinder portion, a small diameter and a large diameter piston respectively reciprecable in said cylinder portions, a receiver, and a single distribution valve, said small diameter cylinder portion having passages near its outer end connected at intervals to said receiver by said piston.

4-0. In a compound pneumatic impact tool, a small diameter and a large diameter cylinder portion, a small diameter and large diameter piston in said cylinder portions, :1 receiver, a valve chamber, and a single distribution valve in said chamber, said small diameter cylinder portion having passages near its outer end connected at intervals to said receiver and one end of said valve by said piston, the opposite end of said valve having constant pressure thereon.

ii. In a compound pneumatic impact tool, a plurality of working cylinder portions of diflerent diameters, pistons of different diameters reciprocable in said cylinder portions, a single valve, means controlled by said single valve for admitting motive fluid to a small diameter cylinder portion, receivers, means admitting expanded motive fluid from said small diameter cylinder portion to such receiver, and means controlled by said single valve for admitting expanded motive fluid from said receiver to a large diameter piston.

42. In a pneumatic tool, a small diameter and a large diameter cylinder portion, a large diameter and a small diameter piston, reciprocable in said cylinder por' tion,-a receiver, a single valve, means controlled by said single valve for intermittently admitting motive fluid into the small diameter cylinder portion, means controlled by said piston for alternately admitting the expanded fluid from the small diameter cylinder portion to the receiver, and means controlled by said single valve for equalizing the pressure of the motive fluid remaining in the small diameter cylinder after the receiver has been filled with motive fluid, between the small diameter cylinder and the space in front of the large piston.

43. In a compound pneumatic impact tool, a working cylinder formed with a small diameter portion and a large diameter portion, a small diameter and a large diameter piston slidable in said cylinder portions, a single valve, means controlled by said valve for admitting motive fluid to said small diameter cylinder portion, a receiver, means controlled by said piston for admitting expanded fluid from said small diameter cylinder portion to said receiver, and means connected to cooperate with the motive fluid admitting means to simultaneously admit expanded fluid from said receiver back of the large diameter piston.

4A. In a compound pneumatic hammer, a barrel having a differential piston cham ber forming high pressure and low pressure cylinders, a plunger therein having high pressure and low pressure piston areas, a receiver, a single distribution valve, means controlled by the latter for simultaneously utilizing live motive fluid on the high pressure area of said plunger and expanded motive fluid from said receiver upon a large area of said plunger to drive said plunger outwardly.

45. In a compound pneumatic impact tool, a small diameter and a large diameter cylinder portion, a large diameter and a small diameter piston reciprocable in said, cylinder portions, a single valve, means controlled by said valve for intermittently admitting motive fluid into the small. diameter cylinder portion, a receiver, means controlled by said piston for conducting expanded motive fluid exhausted from the small diameter cylinder portion to said receiver, and means controlled by said valve for alternately admitting expanded fluid from said receiver to an end of the large diameter cylinder portion.

l6. In a compound pneumatic impact tool, a small diameter and a large diameter cylinder portion, a small diameter and a large diameter piston reciprocable in said cylinder portions, a single valve for intermittently admitting motive fluid into said small diameter cylinder portion, a receiver, means controlled, by said piston for conducting expanded fluid from said cylinder portion to said receiver, means connected to the motive fluid admitting means/to simultaneously admit expanded fluid iromthe receiver to the large diameter-cylinder portion back of the piston in the same, and means controlled by said: single valve for, connecting the opposite ends of the cylinder portions to admit of expanded fluid differentially acting against the pistons.

a7; In a compound pneumatic impact tool, a small. diameter and a large diameter cylinder portion, the latter having an open-, ing for the, shank of the working tool, a small diameterand alarge diameter piston reciprocable in said cylinder portions, passages connected to the opposite ends of said cylinder portions, a receiver, and single controlling valve arranged to intermittently connect said passages, said, single valve also controlling the exhaust from said large diameter piston.

48. In a compound pneumatic impact tool, a small diameter and a large diameter cylinder portion, a small diameter and a large diameter piston reciprocable in said cylinder portions, a receiver, a passage from near the outer end of said small diameter cylinder portion to said receiver, a single valve for intermittently admitting motive fluid. to the small diameter cylinder portion, and a passage from, said receiver to the inner end of the large diameter cylinder portion, said single valve controlling admission of expanded: fluid from said receiver through said passage to said large cylinder portion.

49. In a compound pneumatic impact tool, a small diameter and a It i'ge diameter cylinder portion, a small diameter and large diameter piston reciprocablein said cylinder portions, areceiver, a passage from near the outer end of said small diameter cylinder portion to said receiver, a single valve for intermittently admitting motive fluid to the small diameter cylinder portion, a passage from said receiver to the inner end of the large diameter cylinder portion, said single valve controlling radmission of expanded fluid from said receiver through said passage to said cylinder portion, and a passage between the opposite ends of said cylinder portions also controlled by. said single valve.

50. In a compound-pneumatic impact-tool, a small diameter and a. large diameter cylinder portion, a small diameter and a large diameter piston reciprocable in said cylinder portions, a single valve for intermittently admitting motive fluid into said small diameter cylinder portion, a receiver, a passage from near the end of said; smallv diameter cylinder portion to said receiver, a pas sage connecting said receiver and the upper or inner end of the large diameter cylinder portion, said single valve controlling said passage, the exhaust from said inner end of said large cylinder portion: being also controlled by said single valve, and a passage connecting opposite ends of said cylinder portions, also controlled by said single valve.

51'. In a compound pneumatic tool, a barrel provided with a. differential piston chamber having its front end open to receive the shank of the working tool, a diflerential plunger in said cylinder, a single valve serving as a high pressure inlet controlling valve and as a low pressure exhaust controlling valve, and a receiver coactingwith said valve and piston chamber. 7

52. In a pneumatic hammer, a barrel having a differential piston chamber, the forward end of said barrel being open for the reception of the shank of the working tool, a differential plunger in said piston chamber having pistons of different areas, a receiver, and a single controlling valve for admitting air at initial pressure to the high pressure cylinder and at the same time admitting air from the receiver to the inner end of said low pressure'cylinder, said valve controlling communication between said receiver and said lowpressure piston chamber.

53. In a pneumatic hammer, a barrel having its forward end open for the shank of the working tool and provided with a differential piston chamber, whereby high pressure and low pressure cylinders are formed, a receiver adapted to receive the expanded fluid from the high pressure cylinder and retain it for use when required in the low pressure cylinder, and a single controlling valve for said cylinders and receiver.

54. In a compound pneumatic hammer, a barrel having its forward end open for the shank of the working tool and provided with a diflerential piston chamber, whereby high pressure and low pressure cylinders are formed, a receiver adapted to receive the expanded fluid from the high pressure cylinder and retain it for use when required in a low pressure cylinder, a single controlling valve, ports and passages common to said valve, receiver and piston chamber, and means for causing live air pressure to constantly act upon a portion of said valve to shift the same.

55. In a compound pneumatic hammer, a barrel having its forward end open to receive the shank of theworking tool and having a differential piston chamber therein, a differential plunger located in said piston chamber. and having pistons therein of differentdiameters, a receiver, a single valve for controlling" the inlet and exhaust of motive fluid to and from said piston chamber, and means for causing live motive fluid to act constantly upon an end of said valve for shifting the same.

56. In a compound pneumatic hammer, a barrel having its forward end open for the reception of the shank of a working tool, said cylinder having therein a differential piston chamber, a differential plunger located in said piston chamber, a single valve for controlling the reciprocations of said plunger, means for causing live motive fluid to act constantly upon an end of said valve, a receiver, and connections common to said receiver, piston chamber and said valve, whereby motive fluid is admitted from said receiver to act'expansively upon a low pressure area of said plunger simultaneously with the admission of live motive fluid to the high pressure area of said plunger to augment the momentum of the striking blow of said plunger.

57. In a compound pneumatic impact tool, a barrel having its forward end open to receive the shank of the working tool, a plurality of working cylinder portions of different diameters, a working plunger having pistons of different diameters reciprocable in said cylinder portions, a single valve for admitting motive fluid to a small diameter cylinder portion, a plurality of receivers connected together, and means controlled by said piston for admitting expanded motive fluid from one of said cylinders to such receivers, said single valve admitting expanded motive fluid from said receivers to the cylinder portion of larger diameter to augment the blow of the piston.

58. In a compound pneumatic impact tool, a grasping handle having a pressure supply duct therethrough, means for manually controlling said duct, a valve chamber carried by said handle and adapted to receive a single valve therein, a closure for said valve chamber, a plunger chamber in said closure, and a constantly open passage leading from said pressure supply duct to said plunger chamber, in combination with a barrel, a hammering piston therein, a receiver in said barrel, and passages common to said barrel, receiver and valve chamber.

WILLIAM BUR-LINGHAM.

lVitnesses Gno. A. PARKER, MoG. SINTON. 

